The present invention relates to an information recording technique usable in an authentication system or other systems and, more particularly, to a new method of information processing for recording and reproducing information according to the wavelength of light from a light emitting element.
Conventionally available cardlike recording media include magnetic cards using a magnetic recording technique, IC cards using a semiconductor technique, optical cards using an optical technique, and other similar cards. These recording media are described in xe2x80x9cHandbook for Electronics, Information and Communication Engineersxe2x80x9d, pp. 605, published by the Institute of Electronics, Information, and Communication Engineers of Japan.
For example, the magnetic card has magnetic stripes, and personal information is recorded using the magnetic stripes. The IC card includes an integrated circuit, onto which information is electronically written. In the optical card, pits, which reflect light, are arranged in accordance with information, and thereby information is stored in a bit by bit manner.
In connection with the method of recording information, in the magnetic card, a magnetic material is magnetized in accordance with 1 or 0 of binary data in a manner such that magnetic intensity represents on or off of the bit. In the IC card, binary data is directly written onto an integrated circuit, and the written information is directly read. In the optical card, pits are formed in a light non-reflective layer arranged above a light reflective layer in accordance with 1 or 0 of binary data, and to read them, a laser beam is directed to the pits, thereby reading information responsive to the intensity of the reflected light.
The specifications of the conventional recording medium and the conventional recording method are standardized, and information recording cannot be performed on an individual, low-cost and easy basis. In today""s information society, there is a great demand for recording personal information in a diversity of businesses. Information recording is preferably carried out onto any medium, without the need for magnetic recording media working together with computer or standardized cards. The conventional technique keeps individual users from flexibly recording information without any limitation to media.
The security of information is an important concern in today""s information society. Security cannot be assured in a method in which an imitator is able to easily read information. There is a great demand for the proposal of a new system for information recording. Since the conventional technique requires, in principle, that information be recorded in a binary code, there is the risk that imitators can easily know the content of information if they read, from a recording medium, a signal corresponding to the information.
Since the amount of information at any given recording point in the binary data is one bit at most, the overall amount of information recordable at a limited number of recording points on the recording medium is not so large. By changing physical constants, such as a wavelength of light, a multi-value recording is performed on a single recording point, and the amount of information recorded onto the recording medium will dramatically increase.
It is a first object of the present invention to provide a new information recording method, which has not been available, and thus to provide new methods for recording and reproducing information to enhance the security of information.
It is a second object of the present invention to provide a new information reproducing method which reads information from a recording medium, and thus to provide new methods for recording and reproducing information to enhance the security of information.
It is a third object of the present invention to provide an information recording medium for the new information recording and reproducing methods, and thus to enhance the security of information.
It is a fourth object of the present invention to provide an information recording apparatus for carrying out the new information recording and reproducing methods, and thus to allow individual users to easily record security information and the like.
It is a fifth object of the present invention to provide an information reproducing apparatus for carrying out the new information recording and reproducing methods, and thus to enhance the security of information.
Noticing electroluminescence (EL) in which the emission of light results from the application of an electric field and photoluminescence (PL) in which luminescence is stimulated by the irradiation of light having a particular wavelength, the inventors of this invention have proposed a technique to record, read and reproduce information using the wavelength of the light emission of a light emitting element. The light emitting element is easily formed by appropriately selecting the light emitting material and thanks to the rapidly advanced ink jet technique today, the information recording method using the light emitting element serves individual use at a personal level.
To achieve the first object of the present invention, an information recording method for recording desired information onto a recording medium includes
1) the step of identifying a characteristic of light, which corresponds to information to be recorded, in accordance with a corresponding relationship predetermined between specific information and the characteristic of light,
2) the step of selecting a light emitting material that emits the light having the identified characteristic in response to supplied energy, and
3) the step of arranging the selected light emitting material onto a substrate of the recording medium.
The present invention may further include the step of forming a reflective layer for reflecting the light from the light emitting material, prior to or subsequent to the step of discharging the selected light emitting material.
The xe2x80x9ccharacteristic of lightxe2x80x9d characterizes the property of light by physical constants, and may be anything which is related to information by numerical values, such as the wavelength, frequency, frequency distribution, quantity of light (amplitude of wave). The energy may be anything that stimulates the light emitting element, for example, electricity, light, magnetic field, heat, etc. The light emitting material may be anything that performs a predetermined light emission when supplied with energy. For example, an organic electroluminescence material, an inorganic electroluminescence material, a photoluminescence material or the like may be used. The substrate may be anything that holds the light emitting material thereon. For example, a hard material, such as a bonded glass or ceramic, or a flexible material, such as paper or a plastic film, may be employed. Available as a method for arranging the light emitting material on the substrate is an application method such as a printing method or a roll coating method, or a fluid light emitting material may be applied through an ink jet recording head. The discharging method of discharging the material through the ink jet recording head is preferable as a method for implementing the present invention, because the device for it is simple and easy to control.
To achieve the second object of the present invention, an information reproducing method for reading information from a recording medium, includes
1) the step of emitting light from a light emitting element by supplying energy to a recording medium which includes at least one light emitting element emitting light having a characteristic correspondingly predetermined to specific information,
2) the step of reading the light emitted by the light emitting element,
3) the step of identifying the characteristic of the read light, and
4) the step of identifying unique information indicated by the identified characteristic of the light, in accordance with a corresponding relationship between the identified information and the characteristic of the light.
The information recording method may further include the step of comparing the identified unique information to a set of authentication information pre-registered in a database, and the step of processing the recording medium as being authenticated, when there is present, in the set of authentication information, information identical to the unique information.
To achieve the third object of the present invention, a recording medium includes at least one light emitting element, for information holding, which emits light having a specific characteristic with energy supplied thereto, and includes a light emitting material that emits light having a characteristic corresponding to the unique information to be recorded, in accordance with a corresponding relationship predetermined between specific information and the characteristic of the light.
Preferably, the light emitting element includes a reflective layer for reflecting the light from the light reflecting material, and the reflective layer has an optical resonance structure matching the characteristic of the light emitted by the light emitting material.
For example, the light emitting element may be an electroluminescence element. Preferably, the light emitting element is an organic electroluminescence element, and further includes a hall transport layer. Preferably, the light emitting element is an organic electroluminescence element, and further includes an electron transport layer. The light emitting element may be an element emitting light based on photoluminescence.
To achieve the fourth object of the present invention, an information recording apparatus for recording desired information onto a recording medium, includes
1) a plurality of storage means for storing light emitting materials, which emit lights having respective specific characteristics in response to energy supplied thereto, in accordance with a corresponding relationship between the light emitting material and the specific characteristic,
2) control means for selecting one of the plurality of storage means, and
3) discharging means for discharging, onto a substrate, the light emitting material supplied by the storage means selected by the control means, wherein when the unique information to be recorded is supplied, the control means identifies the characteristic of the light indicating the unique information in accordance with the corresponding relationship predetermined between the specific information and the characteristic of the light and selects the light emitting material emitting the light having the identified characteristic.
The information recording apparatus may include reflective layer forming means for forming a reflective layer reflecting light from the light emitting material, prior to or subsequent to the discharging of the light emitting material.
Preferably, the discharging means is an ink jet recording head, and the information recording apparatus further includes driving means for relatively moving the ink jet recording head with respect to the substrate.
To achieve the fifth object of the present invention, an information reproducing apparatus for reading information from a recording medium, includes
1) energy supplying means which is arranged to supply predetermined energy to a recording medium which includes at least one light emitting element emitting light having a characteristic correspondingly predetermined to specific information,
2) detecting means for detecting the light emitted by the light emitting element in response to the energy,
3) identifying means for identifying the characteristic of the detected light, and
4) processing means for identifying unique information indicated by the identified characteristic of the light in accordance with a corresponding relationship between the identified information and the characteristic of the light.
As the energy supplying means, electrodes that feed a current or an electric field, or a lamp or a laser device, which feeds optical energy, is employed. As the detecting means, an optical fiber or other optical element, which inputs directly the wavelength of light, or a photoelectric conversion device which detects the intensity of light is employed. The identifying means is a spectrometer, a spectrum analyzer, or the like when the characteristic of light is a wavelength, and is level detecting means, such as a peak detector, when the characteristic of light is intensity. The processing means decodes the output signal of the identifying means, and is preferably a microcomputer, or the processing means may be constructed of a decode circuit in hardware.
In the information reproducing apparatus, the energy supplying means is preferably arranged to supply one of electricity and light to the light emitting element as energy.
The information reproducing apparatus further includes a database for storing a set of predetermined authentication information, and the processing means compares the identified unique information to the set of authentication information registered in the database when the unique information is identified, and processes the recording medium as being authenticated when there is present, in the set of authentication information, information identical to the unique information.